The study on using smectic liquid crystal as display material has a history of over 30 years. Monitors using the smectic liquid crystals as the display materials are reflective display devices, which have no polarizer plate and backlight, compared with common liquid crystal display devices. Such monitors rely mainly on reflection of external light, resulting in lower contrast and making commercialization more difficult.
The study on the smectic liquid crystal material is focused on ferroelectric liquid crystal and antiferroelectric liquid crystal that belong to smectic A phase and smectic C phase. The ferroelectric liquid crystal and antiferroelectric liquid crystal materials are used in surface stabilized display devices. Since uniform, perfect and regular arrangement is required for both the liquid crystal molecules and the liquid crystal layers in this kind of devices, and the thickness of a liquid crystal cell is required to be 1 to 2 μm, the manufacturing process of such devices is very difficult, and large scale production cannot be achieved, so the ferroelectric liquid crystal devices have not enter a practical commercial application stage.
There are few smectic liquid crystal materials. WO 2010/070606 A1 discloses a method for obtaining a wide-temperature range smectic phase. Actual tests show that the contrast of this material is undesirable, making it infeasible to be used in actual display devices.
Therefore, in the field of display application of multi-stable liquid crystals, there is an urgent need for a high scattering smectic liquid crystal material that can be used in display devices having an excellent optical structure, so as to increase the contrast of the smectic crystal display devices and achieve a good display effect.